In a world where technological advancements move at lightning speed, the semiconductor industry is facing unprecedented challenges. The demand for smaller, faster, and more energy-efficient devices is growing, and traditional manufacturing processes are being pushed to their limits. Enter Spin-on Dielectrics (SOD), a breakthrough material technology that offers a cost-effective, scalable solution for micro-gap filling and high-performance dielectric films. As the industry evolves, SOD is expected to play a pivotal role in enabling the next generation of chips that power everything from AI to everyday electronics.To learn more, SEMI Europe and Merck KGaA, Darmstadt, Germany, held a joint webinar that focused on semiconductor device process evolution by SOD. The session featured insights from three technology experts in the company, including Dr. Surésh Rajaraman, Executive Vice President and Head of Thin Film Business Unit, along with Atsuko Yamamoto, R D Manager for Spin-On Dielectric, and Go Nakano, Global Marketing Manager for Dielectric Materials.SEMI: What is SOD, and how does it fit within the broader semiconductor manufacturing process?Rajaraman: SOD, Spin on Dielectrics, is a unique class of materials used to deposit thin layers of dielectric films, which act as insulators or other functional films, on semiconductor devices. The fabrication of a semiconductor chip involves thousands of intricate steps that incorporate conductors, semiconductors, and insulators. SOD is a versatile technology that supports device performance and miniaturization by enabling better gap fill and film uniformity, all while offering attractive cost of ownership.SEMI: Why is there so much focus on SOD materials, and how are they evolving to meet future industry demands?Rajaraman: As semiconductor devices become more complex—such as 3D NAND scaling to more than 300 layers and DRAM incorporating pillar capacitors—there’s a growing need for materials that can address challenges like interconnect delays, power consumption, and heat generation while maintaining optimal performance. Traditional dielectric materials are reaching their limits, making Spin-on Dielectrics (SOD) a critical solution. SOD offers advantages like bottom-up and seam-free gap filling, enabling ultra-thin insulating and other functional layers that enhance electrical and thermal efficiency and support next-generation device scaling.The industry is pushing the boundaries of scaling, with increasing aspect ratios and complex structures in Logic, 3D NAND and DRAM. Modern devices now require deposition in features which are not only incredibly narrow but also increasingly deep due to going into the third dimension. This creates new challenges, such as stress buildup and cracking in conventional SOD materials. To overcome this, we are developing enhanced formulations with improved mechanical stability and polymer backbone engineering. These innovations enhance gap-filling properties and resistance to process-induced stress, ensuring SOD remains a key enabler for advanced semiconductor manufacturing.SEMI: What are the current industry trends driving the adoption of SOD?Nakano: SOD is becoming a key technology because of its excellent gap-filling performance. Unlike gas-phase deposition methods like Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD), SOD is a liquid-phase process. This makes it more efficient for high-aspect-ratio structures. It also helps reduce costs while maintaining high-performance dielectric properties.With increasing demand for high-density memory and logic devices, SOD is crucial for applications like DRAM and NAND flash, which require precise dielectric layer formation. In DRAM, we’re witnessing a shift from planar to vertical transistors, and even to monolithic 3D DRAM. These changes require new materials for gate insulators and electrodes, alongside improvements in aspect ratio gap filling.For NAND memory, manufacturers are increasing the number of memory layers, leading to taller memory stacks and deeper trenches. As lateral scaling progresses, narrower and more complex structures demand high-aspect-ratio trench fills to maintain performance and reliability.Logic devices are also evolving, with transistor structures moving from FinFETs to nanosheets and forksheets. This transition enhances performance, but it also introduces challenges in wiring density and electrical properties. The narrower pitch of wiring requires advanced dielectric solutions, like SOD, to enable reliable, high-performance semiconductor architectures.SEMI: With all these recent innovations, what role does Merck KGaA, Darmstadt, Germany play in supporting these advancements, and what does the company offer its customers? Rajaraman: As the semiconductor industry pushes the boundaries of scaling, doing so requires materials that can support increasingly complex structures. We are the only materials company in the industry to possess the full spectrum of process technologies for gap-filling capabilities, including SOD, ALD, CVD, and Flowable CVD. Our strategic acquisition of Versum Materials has expanded our capabilities with organosilicon precursors. Combined with our SOD expertise, it allows us to reengineer material backbones with more material choices and tailored properties to optimize performance in high-aspect-ratio applications.To support this, we’ve expanded our global R D footprint. We now operate in various application labs, enabling close collaboration with customers for material customization and fine-tuning properties to address specific manufacturing challenges. Last year, we inaugurated a new R D center in Korea as part of our commitment to being near our customers and accelerating time-to-market for next-generation semiconductor solutions. As semiconductor roadmaps become more complex, customization and collaboration also become more critical. The key to innovation lies in working closely with our customers, understanding their challenges, refining materials, and optimizing processes together. By fostering this ongoing partnership, we can accelerate technological advancements and ensure that new solutions align seamlessly with evolving industry demands.SEMI: Can you share some technical insights on SOD?Yamamoto: SOD is a key material used in semiconductor manufacturing to create insulating layers with high precision. One of the essential components in SOD is PHPS (Perhydropolysilazane), a polymer composed of silicon, nitrogen, and hydrogen. This material is applied as a liquid solution and transforms into a high-quality silicon oxide film through a series of thermal processes.PHPS is essential because it enables precise gap filling in extremely small structures, helping to improve device reliability. The process involves spin-coating the polymer onto a wafer, followed by pre-baking to remove solvents. Then, it undergoes high temperature curing in an oxygen and steam atmosphere, forming a dense silicon oxide film. This method ensures uniform coverage and cost efficiency compared to traditional dry film deposition techniques.Our Spinfil® product line has evolved over the past two decades, starting with the Spinfil® 400 series and advancing through the Spinfil® 600 to the widely used Spinfil® 800 series. These improvements have enhanced gap-filling capabilities and film uniformity, making them ideal for high-aspect-ratio trench structures. The critical baking process involves spin coating and pre-baking before wafers undergo batch processing in a high-temperature furnace. Controlled temperature and moisture conditions transform Spinfil® into silicon oxide films, optimizing properties such as refractive index, shrinkage, and etching resistance and ensuring reliability in semiconductor applications.SEMI: What are the latest trends in new polymer development for SOD?Yamamoto: Our research focuses on three key areas: enhancing film quality, developing SOD for high-aspect-ratio trench filling, and advancing low-k SOD for semiconductor processes.To improve film quality, we introduced the Neofil®series, an evolution of the Spinfil® 800 series. This innovation reduces film shrinkage, lowers stress, and enhances wet etching rates, making it ideal for next-generation semiconductor nodes.Our latest Neofil® series for high-aspect-ratio trench filling is targeted for traditional dry processes like CVD and ALD, which can often lead to void formation and require multiple deposition-etch steps. Our latest SOD materials address this by improving polymer elasticity, ensuring uniform filling of deep trenches up to 16 microns without cracks, making them suitable for emerging 3D nanostaircase designs.In low-k SOD development, we’re focusing on siloxane-based polymers, which provide excellent trench-filling capabilities while maintaining strong mechanical and electrical properties. Compared to flowable CVD and ALD, SOD offers a more cost-effective and efficient alternative. With continued advancements, we anticipate SOD will become a key material for future semi-damascene processes, enhancing embedding performance and overall device reliability.SEMI ContactSitong He, Communications Manager Email: [email protected]